Although having bluish colored nails can sometimes be a sign of a problem with low oxygen levels in the blood, this is usually a long standing problem due to something like a heart condition, and it would be extremely unlikely to present like this when you are 28 years old.
Nevertheless, if you have not mentioned this to your primary care doctor
, you should do so. They will be able to do a complete physical examination to make sure their is nothing amiss. If you have other concerning symptoms, such as palpitations, dizziness
or passing out, chest pain, or shortness of breath you should mention those symptoms to your doctor as well.
Some people have variations in the flow of blood to their fingers and toes, which leads to periodic purple coloring of the fingernails and tips of the fingers or toes, especially in cold weather. When this is severe, and associated with pain or with episodes where the skin actually turns white due to lack of blood flow, this is called Raynaud's phenomenon. Raynaud's is relatively common, but it should always be evaluated by a doctor, because sometimes it is a sign of an underlying connective tissue disorder.